jeffhi@microsoft.UUCP (Jeff HINSCH) (11/06/90)
I'm having a problem eliminating moire patterns from screendumps that I'm imaging on an L300/RIP 2. Has anyone else dealt with this before? The problem arises in dithered images where there are many different colored pixels packed closely together. A LaserWriter exhibits the moire problems as blocks of varying grey-scale, but the L300 (running at 1270dpi) produces lovely plaids and abstract patterns. The best solution I've come up with so far is to run the images at 134+ lines of resolution, but the offset people can't handle more than 130 and prefer ~120. Next best is to use a 90 degree angle, but the output is not very appealing to the eye--everything appears to be marching down the page in columns and there are still some combinations of dithered color that produce moire at 90. My next effort was to try a line screen at a flat angle, but that is truely ugly. I suppose I could use traditional methods as a model: I'd strip all the yellow out of the bitmap making a new bitmap and image it at a unique angle (30 is recommended I believe), return to the image origin and lay down the stripped-out blue portion of the image at a different angle, etc. But before I cripple my current production methods I thought I'd ask you to share your experiences along this line. Thanks for any help you can provide. ------------ only UNIX cripples don't have a sig.